1. Field of the Invention
The present invention relates to an apparatus for counting viable particles in a liquid, and in particular, to an apparatus which detects viable particles existing in a liquid in real time.
2. Description of the Related Art
In the detection of viable particles, there have been known a method of cultivation (official analytical method), a microcolony method, an ATP (luciferase) method, a fluorescent dye method, an autofluorescence method, and so on. Among these detection methods, a detection method enabling to obtain the result on the presence/absence of the viable particles in real time is the autofluorescence method. This autofluorescence method is a detection method of viable particles utilizing an autofluorescence light emitted from the viable particles. A concrete autofluorescence method detects the viable particles by utilizing the following phenomenon. This phenomenon is a phenomenon that, when a light with a predetermined wavelength is first radiated to a given substance, an energy state that this substance has is excited (the substance absorbs the radiated light), and thereafter the substance emits extra energy to the outside as fluorescence at the time of returning to a ground state from the excited state. Further, when irradiated with a light having a wavelength unique to the substance, the substance easily emits an autofluorescence light to the outside. This is because the wavelength easily causing the substance to absorb the light differs depending on each substance.
There is an art to confirm the presence/absence of viable particles based on whether or not an autofluorescence light is detected, by utilizing this autofluorescence phenomenon. For this purpose, in this art, an ultraviolet ray is radiated to a water medium. This art uses a filter that selects a specific part (wavelength band) of the autofluorescence light that is to be measured.
However, when the ultraviolet ray is radiated to the water, a Raman-scattered light by water is also detected in addition to the autofluorescence light. This is because the radiated ultraviolet ray is scattered by the water (Raman scattering). Concretely, the Raman-scattered light longer in wavelength than the radiated ultraviolet ray is emitted. Therefore, it becomes difficult to detect the presence/absence of only the viable particles by using the autofluorescence light as an index. Further, even if the autofluorescence light only whose specific region is selected is detected, it is difficult to detect the presence/absence of the viable particles. This is because the Raman-scattered light which has the same wavelength as that of the autofluorescence light is emitted from the liquid, depending on the wavelength of the radiated ultraviolet ray.
Further, conventionally, in the manufacture of a dialysis fluid administered to a human body, the dialysis fluid is first treated to a state not causing a problem even when administered to a human body, by filtering out viable particles by a filter or the like. Then, regarding the manufactured dialysis fluid, it is inspected whether or not the viable particles exist in the dialysis fluid by an inspection method such as a method of cultivation (official analytical method) or a fluorescent dye method. Further, in blood dialysis to a human body, a dialysis fluid is made to flow in a specific medical instrument and blood having undergone the blood dialysis there is administered to a human body. This flowing dialysis fluid also undergoes a filtration treatment to be manufactured and managed, and similarly undergoes a viable particle inspection.
In the inspection by the method of cultivation, the viable particles in the dialysis fluid are cultivated on a bleeding ground under a condition of low temperature and a long period (several days to one week) and it is confirmed whether or not a colony is formed. In this manner, it is inspected whether or not the viable particles exist. Further, in the inspection by the florescent dye method, a specific dyeing reagent is dropped to the dialysis fluid, and after several-minute dyeing, light is radiated, followed by photographing by a CCD camera or the like, and the number of points emitting light is counted. In this manner, it is determined whether or not the viable particles exist and the number of the viable particles is counted.
Here, when the dialysis fluid inspection is performed by the fluorescent dye method, every time the inspection is performed, it is necessary to move the dialysis fluid to a place different from a place where the blood dialysis is performed, perform the dyeing process by the specific dyeing reagent, and count the number of the viable particles after the photographing by the CCD camera. Further, it takes about twenty minutes to confirm the result of the inspection of the dialysis fluid. Therefore, it is not possible to perform the inspection in real time during the blood dialysis.
Further, conventionally, water sent from a purified water basin provided in a water purification plant, an aquarium, a lake or a marsh, a garden, or the like is purified by filtration, disinfection, or the like in order to purify the water by eliminating and killing viable particles contained in the water. Further, regarding this purified water, it is inspected by a turbidimeter, a fine particle counter, or the like whether or not sterilizing purification of the viable particles is performed efficiently.
For example, in the inspection by the turbidimeter, turbidity is calculated, and from this turbidity, a probability that viable particles in water are eliminated by sterilizing purification is calculated. A concrete inspection method is performed by radiating a light to the water containing particles (viable particles or non-viable particles), and comparing the light radiated from a light source and a scattered light received by a light receiving apparatus, or detecting an interference light due to the particles. Further, by using the fine particle counter, it is confirmed whether or not a specific pathogenic worm (for example, cryptosporidium) in water is eliminated by the sterilizing purification. In a concrete confirmation method, a fluorescent labeled antibody easily bonding with the pathogenic worm being the detection target is mixed with the purified water, and it is confirmed whether or not the water is purified by sterilization based on whether or not a fluorescence light emitted from the detection target is detected.
In this method, the real-time inspection of the water having undergone the purification treatment is not possible. This is because, as the detection method, an antigen-antibody reaction is utilized by using chemicals such as the fluorescent labeled antibody. For example, it takes twenty minutes to thirty minutes at 37° C. or one hour or more at room temperature for the antigen-antibody reaction between cryptosporidium and the fluorescent labeled antibody to end. Further, since the detection target has been purified and thus its amount is only a little, a large amount of the fluorescent labeled antibody is required in order to easily cause the antigen-antibody reaction.
In addition, preliminary arrangements for the inspection such as filtering the water having undergone the purification treatment by using a filter with a 3μ pore size, capturing and condensing large fine particles containing the cryptosporidium on a surface of the filter, and thereafter using the fluorescent labeled antibody are required in advance. Here, when the inspection (detection) of viable particles other than cryptosporidium is performed, it is necessary to use another fluorescent labeled antibody easily undergoing an antigen-antibody reaction with the viable particles. Therefore, the inspection method utilizing the antigen-antibody reaction with the viable particles has problems that it requires a predetermined time to confirm the inspection result, a plurality of kinds of the fluorescent labeled antibodies have to be prepared, and the purified water has to be condensed or a large amount of the fluorescent labeled antibody has to be prepared.